1. Field of the Invention
The invention relates to a color sensor system for the recognition of objects with surfaces that are at least partially colored.
2. Description of the Prior Art
In conventional color recognition devices operating according to a three-area process, the objects to be recognized are illuminated with, for example, white light from a halogen lamp. The reflected light is decomposed by means of lenses and standard color filters into the primary colors, red, green and blue. The intensity of the individual color components is then converted into electrical signals by photosensors which are connected to receiving amplifiers. The amplified electrical signals are fed into an arithmetic unit for a color determination. It has also already been suggested that instead of standard color filters with following photosensors, color-sensitive photodiodes to which the light reflected from a colored object is fed through an objective lens, should be used. In this case, for a color determination, a temperature compensation is made for the electrical signals supplied by the photodiodes.
In addition, a color sensor system is already known (European Published patent application No. EP-A-0 109 686), which has a plurality of electronic light transmitters emitting light of various wavelengths, which, in succession, briefly illuminate an object whose color is to be determined with light pulses of the same intensity. The light reflected from the object is conducted to a photosensor, which converts the light signals into electrical signals and conducts the latter to an evaluation device for an evaluation. In the course of this evaluation, the presence of the color components determined by the individual light transmitters is checked with the aid of a threshold-value indicator on the basis of the electrical signals that occur in succession only. On the other hand, no provision is made for a quantitative evaluation of the intensity of the individual color components, such as is necessary, for example, for a determination of arbitrary mixed colors.
Accordingly, it is the object of the present invention to describe a color sensor system by means of which a color determination with a high degree of accuracy can be made.